1 files changed, 7 insertions, 0 deletions

diff --git a/include/linux/sched/user.h b/include/linux/sched/user.h
index c7b5f86b91a1..468d2565a9fe 100644
--- a/include/linux/sched/user.h
+++ b/include/linux/sched/user.h
@@ -31,6 +31,13 @@ struct user_struct {
         atomic_long_t pipe_bufs;  /* how many pages are allocated in pipe buffers */
 
 #ifdef CONFIG_KEYS
+        /*
+         * These pointers can only change from NULL to a non-NULL value once.
+         * Writes are protected by key_user_keyring_mutex.
+         * Unlocked readers should use READ_ONCE() unless they know that
+         * install_user_keyrings() has been called successfully (which sets
+         * these members to non-NULL values, preventing further modifications).
+         */
         struct key *uid_keyring;        /* UID specific keyring */
         struct key *session_keyring;    /* UID's default session keyring */
 #endif